With the development of science and technology, flat panel display monitors have replaced bulky CRT monitors and deeply embedded into people's daily routines. At present, common flat panel display monitors include liquid crystal display (LCD) and organic light-emitting diode display. Particularly, the LCD flat panel display has been rapidly developed in recent years and dominated the current flat-panel display market due to its characteristics such as small size, light weight, thin, low power consumption and no radiation, and has been widely used in products of various sizes, which almost cover main electronic products in today's information society, such as LCD TVs, computers, cell phones, PDA, GPS, vehicle display, projection display, video cameras, digital cameras, electronic watches, calculators, electronic equipment, instruments, public display and unreal display.
In an imaging process, in cooperation with a periphery driving circuit, each liquid crystal pixel in the LCD monitor is driven by a thin film transistor (TFT) integrated in a TFT array substrate to realize displaying of images. In an active matrix organic light emission display (OLED), in cooperation with a periphery driving circuit, TFT in a TFT array substrate drives a corresponding OLED pixel of the OLED panel to realize displaying of images. In the above display, TFT is a switch for controlling light emission, is a key for realizing a large-size LCD display and OLED display, and directly affects development direction of high performance flat panel display.
In the existing production technology of flat panel display monitors, industrial TFT mainly includes amorphous silicon TFT, poly-silicon TFT, and mono-crystalline silicon TFT, etc. Most of array substrates in the flat panel display monitors are manufactured by adopting amorphous silicon TFT. At present, with the development of technology, the metal oxide TFT appears. The metal oxide TFT has advantages of high carrier mobility, thus, TFT can be made in a smaller size, thereby to enable the flat panel display monitor to have a higher resolution and better display effect. In addition, the metal oxide TFT has further advantages such as less characteristic inequality, material and process of low cost, low process temperature, capable of being used in coating process, high transparency, large band gap. Therefore, application of the metal oxide TFT in the flat panel display monitor receives much concern.
At present, generally six times of lithography process are adopted to manufacture the metal oxide TFT, this mainly because a metal oxide semiconductor layer may be corroded when etching source and drain metal electrodes and thus an etching stop layer is added on the metal oxide semiconductor layer to prevent the metal oxide semiconductor layer from being corroded by etching liquid when etching the source and drain metal electrodes. Generally, the fewer the mask plates used when manufacturing the metal oxide TFT, the higher the production efficiency and the lower the cost.